Conventional belt conveyors typically have a plurality of scraper assemblies disposed to remove deposits adhering to the surface of the conveyor belt. For example, it is common to provide a scraper assembly at or near the head pulley to clean the belt as the belt begins its return travel. Additionally, trailing arm scrapers are commonly located along the length of the belt in between the head and tail pulleys to provide additional cleaning.
A common type of scraper blade assembly comprises a plurality of mounted scraper blades extending across the transverse axis of the conveyor belt. The blades are mounted on support arms which are fixed to and extend from a transverse rotatable support shaft. Rotation of the transverse support shaft moves the scraper blades into and out of contact with the conveyor belt. Applying a torque to the support shaft increases the contacting force of the scraper blades against the belt.
During installation and use of the scraper blade assemblies, the belt scraper blades wear down.
A high durometer polyurethane scraping blade will not wear as quickly as a lower durometer blade, but the higher durometer blade will impart greater stress to the conveyor belt and it is more likely to damage poorly-made splices in the conveyor belt, and is less able to adapt itself to conform to the contour of the belt as it wears.
Where it is desirable to provide more flex in the scraper blade, it is desirable to use a 82-85 durometer blade which has a thickness of 11/4" or less. When conventional blades of the prior art are used, the thickness of the blade gradually increases from the tip all the way back to the mounting base, and the greatest flexibility is at the tip where the blade sharply tapers to a relatively sharp edge along its length. After the blade wears through the sharply-tapered tip, the conventional blade loses its high flexibility.
With wet and sticky materials or materials which accumulate due to freezing or evaporation, the scraper blade tends to accumulate materials scraped from the belt on the under surface of the blade which confronts the belt. If the material accumulated on the blade builds up to a substantial degree, it cakes on the under surface and may engage the belt downstream from the scraping edge of the blade and cause the scraping edge to disengage the surface of the belt, or may serve as a dam or block against the bias of the blade holder forcing the scraping edge of the blade against the belt to take advantage of the flexible nature of the blade.